const BLACKLISTED_COMMAND_REGEX = new RegExp(
  `\
\\\\\
(label\
|[a-z]{0,16}ref\
|usepackage\
|begin\
|end\
|[a-z]{0,16}cite\
|input\
|include\
|includegraphics)\
(\\[[^\\]]*\\])?\
\\{[^}]*\\}\
`,
  'g'
)
// Regex generated from /\\?['\p{L}]+/g via https://mothereff.in/regexpu.
// \p{L} matches unicode characters in the 'letter' category, but is not supported until ES6.
const WORD_REGEX = /\\?(?:['A-Za-z\xAA\xB5\xBA\xC0-\xD6\xD8-\xF6\xF8-\u02C1\u02C6-\u02D1\u02E0-\u02E4\u02EC\u02EE\u0370-\u0374\u0376\u0377\u037A-\u037D\u037F\u0386\u0388-\u038A\u038C\u038E-\u03A1\u03A3-\u03F5\u03F7-\u0481\u048A-\u052F\u0531-\u0556\u0559\u0561-\u0587\u05D0-\u05EA\u05F0-\u05F2\u0620-\u064A\u066E\u066F\u0671-\u06D3\u06D5\u06E5\u06E6\u06EE\u06EF\u06FA-\u06FC\u06FF\u0710\u0712-\u072F\u074D-\u07A5\u07B1\u07CA-\u07EA\u07F4\u07F5\u07FA\u0800-\u0815\u081A\u0824\u0828\u0840-\u0858\u08A0-\u08B4\u08B6-\u08BD\u0904-\u0939\u093D\u0950\u0958-\u0961\u0971-\u0980\u0985-\u098C\u098F\u0990\u0993-\u09A8\u09AA-\u09B0\u09B2\u09B6-\u09B9\u09BD\u09CE\u09DC\u09DD\u09DF-\u09E1\u09F0\u09F1\u0A05-\u0A0A\u0A0F\u0A10\u0A13-\u0A28\u0A2A-\u0A30\u0A32\u0A33\u0A35\u0A36\u0A38\u0A39\u0A59-\u0A5C\u0A5E\u0A72-\u0A74\u0A85-\u0A8D\u0A8F-\u0A91\u0A93-\u0AA8\u0AAA-\u0AB0\u0AB2\u0AB3\u0AB5-\u0AB9\u0ABD\u0AD0\u0AE0\u0AE1\u0AF9\u0B05-\u0B0C\u0B0F\u0B10\u0B13-\u0B28\u0B2A-\u0B30\u0B32\u0B33\u0B35-\u0B39\u0B3D\u0B5C\u0B5D\u0B5F-\u0B61\u0B71\u0B83\u0B85-\u0B8A\u0B8E-\u0B90\u0B92-\u0B95\u0B99\u0B9A\u0B9C\u0B9E\u0B9F\u0BA3\u0BA4\u0BA8-\u0BAA\u0BAE-\u0BB9\u0BD0\u0C05-\u0C0C\u0C0E-\u0C10\u0C12-\u0C28\u0C2A-\u0C39\u0C3D\u0C58-\u0C5A\u0C60\u0C61\u0C80\u0C85-\u0C8C\u0C8E-\u0C90\u0C92-\u0CA8\u0CAA-\u0CB3\u0CB5-\u0CB9\u0CBD\u0CDE\u0CE0\u0CE1\u0CF1\u0CF2\u0D05-\u0D0C\u0D0E-\u0D10\u0D12-\u0D3A\u0D3D\u0D4E\u0D54-\u0D56\u0D5F-\u0D61\u0D7A-\u0D7F\u0D85-\u0D96\u0D9A-\u0DB1\u0DB3-\u0DBB\u0DBD\u0DC0-\u0DC6\u0E01-\u0E30\u0E32\u0E33\u0E40-\u0E46\u0E81\u0E82\u0E84\u0E87\u0E88\u0E8A\u0E8D\u0E94-\u0E97\u0E99-\u0E9F\u0EA1-\u0EA3\u0EA5\u0EA7\u0EAA\u0EAB\u0EAD-\u0EB0\u0EB2\u0EB3\u0EBD\u0EC0-\u0EC4\u0EC6\u0EDC-\u0EDF\u0F00\u0F40-\u0F47\u0F49-\u0F6C\u0F88-\u0F8C\u1000-\u102A\u103F\u1050-\u1055\u105A-\u105D\u1061\u1065\u1066\u106E-\u1070\u1075-\u1081\u108E\u10A0-\u10C5\u10C7\u10CD\u10D0-\u10FA\u10FC-\u1248\u124A-\u124D\u1250-\u1256\u1258\u125A-\u125D\u1260-\u1288\u128A-\u128D\u1290-\u12B0\u12B2-\u12B5\u12B8-\u12BE\u12C0\u12C2-\u12C5\u12C8-\u12D6\u12D8-\u1310\u1312-\u1315\u1318-\u135A\u1380-\u138F\u13A0-\u13F5\u13F8-\u13FD\u1401-\u166C\u166F-\u167F\u1681-\u169A\u16A0-\u16EA\u16F1-\u16F8\u1700-\u170C\u170E-\u1711\u1720-\u1731\u1740-\u1751\u1760-\u176C\u176E-\u1770\u1780-\u17B3\u17D7\u17DC\u1820-\u1877\u1880-\u1884\u1887-\u18A8\u18AA\u18B0-\u18F5\u1900-\u191E\u1950-\u196D\u1970-\u1974\u1980-\u19AB\u19B0-\u19C9\u1A00-\u1A16\u1A20-\u1A54\u1AA7\u1B05-\u1B33\u1B45-\u1B4B\u1B83-\u1BA0\u1BAE\u1BAF\u1BBA-\u1BE5\u1C00-\u1C23\u1C4D-\u1C4F\u1C5A-\u1C7D\u1C80-\u1C88\u1CE9-\u1CEC\u1CEE-\u1CF1\u1CF5\u1CF6\u1D00-\u1DBF\u1E00-\u1F15\u1F18-\u1F1D\u1F20-\u1F45\u1F48-\u1F4D\u1F50-\u1F57\u1F59\u1F5B\u1F5D\u1F5F-\u1F7D\u1F80-\u1FB4\u1FB6-\u1FBC\u1FBE\u1FC2-\u1FC4\u1FC6-\u1FCC\u1FD0-\u1FD3\u1FD6-\u1FDB\u1FE0-\u1FEC\u1FF2-\u1FF4\u1FF6-\u1FFC\u2071\u207F\u2090-\u209C\u2102\u2107\u210A-\u2113\u2115\u2119-\u211D\u2124\u2126\u2128\u212A-\u212D\u212F-\u2139\u213C-\u213F\u2145-\u2149\u214E\u2183\u2184\u2C00-\u2C2E\u2C30-\u2C5E\u2C60-\u2CE4\u2CEB-\u2CEE\u2CF2\u2CF3\u2D00-\u2D25\u2D27\u2D2D\u2D30-\u2D67\u2D6F\u2D80-\u2D96\u2DA0-\u2DA6\u2DA8-\u2DAE\u2DB0-\u2DB6\u2DB8-\u2DBE\u2DC0-\u2DC6\u2DC8-\u2DCE\u2DD0-\u2DD6\u2DD8-\u2DDE\u2E2F\u3005\u3006\u3031-\u3035\u303B\u303C\u3041-\u3096\u309D-\u309F\u30A1-\u30FA\u30FC-\u30FF\u3105-\u312D\u3131-\u318E\u31A0-\u31BA\u31F0-\u31FF\u3400-\u4DB5\u4E00-\u9FD5\uA000-\uA48C\uA4D0-\uA4FD\uA500-\uA60C\uA610-\uA61F\uA62A\uA62B\uA640-\uA66E\uA67F-\uA69D\uA6A0-\uA6E5\uA717-\uA71F\uA722-\uA788\uA78B-\uA7AE\uA7B0-\uA7B7\uA7F7-\uA801\uA803-\uA805\uA807-\uA80A\uA80C-\uA822\uA840-\uA873\uA882-\uA8B3\uA8F2-\uA8F7\uA8FB\uA8FD\uA90A-\uA925\uA930-\uA946\uA960-\uA97C\uA984-\uA9B2\uA9CF\uA9E0-\uA9E4\uA9E6-\uA9EF\uA9FA-\uA9FE\uAA00-\uAA28\uAA40-\uAA42\uAA44-\uAA4B\uAA60-\uAA76\uAA7A\uAA7E-\uAAAF\uAAB1\uAAB5\uAAB6\uAAB9-\uAABD\uAAC0\uAAC2\uAADB-\uAADD\uAAE0-\uAAEA\uAAF2-\uAAF4\uAB01-\uAB06\uAB09-\uAB0E\uAB11-\uAB16\uAB20-\uAB26\uAB28-\uAB2E\uAB30-\uAB5A\uAB5C-\uAB65\uAB70-\uABE2\uAC00-\uD7A3\uD7B0-\uD7C6\uD7CB-\uD7FB\uF900-\uFA6D\uFA70-\uFAD9\uFB00-\uFB06\uFB13-\uFB17\uFB1D\uFB1F-\uFB28\uFB2A-\uFB36\uFB38-\uFB3C\uFB3E\uFB40\uFB41\uFB43\uFB44\uFB46-\uFBB1\uFBD3-\uFD3D\uFD50-\uFD8F\uFD92-\uFDC7\uFDF0-\uFDFB\uFE70-\uFE74\uFE76-\uFEFC\uFF21-\uFF3A\uFF41-\uFF5A\uFF66-\uFFBE\uFFC2-\uFFC7\uFFCA-\uFFCF\uFFD2-\uFFD7\uFFDA-\uFFDC]|\uD800[\uDC00-\uDC0B\uDC0D-\uDC26\uDC28-\uDC3A\uDC3C\uDC3D\uDC3F-\uDC4D\uDC50-\uDC5D\uDC80-\uDCFA\uDE80-\uDE9C\uDEA0-\uDED0\uDF00-\uDF1F\uDF30-\uDF40\uDF42-\uDF49\uDF50-\uDF75\uDF80-\uDF9D\uDFA0-\uDFC3\uDFC8-\uDFCF]|\uD801[\uDC00-\uDC9D\uDCB0-\uDCD3\uDCD8-\uDCFB\uDD00-\uDD27\uDD30-\uDD63\uDE00-\uDF36\uDF40-\uDF55\uDF60-\uDF67]|\uD802[\uDC00-\uDC05\uDC08\uDC0A-\uDC35\uDC37\uDC38\uDC3C\uDC3F-\uDC55\uDC60-\uDC76\uDC80-\uDC9E\uDCE0-\uDCF2\uDCF4\uDCF5\uDD00-\uDD15\uDD20-\uDD39\uDD80-\uDDB7\uDDBE\uDDBF\uDE00\uDE10-\uDE13\uDE15-\uDE17\uDE19-\uDE33\uDE60-\uDE7C\uDE80-\uDE9C\uDEC0-\uDEC7\uDEC9-\uDEE4\uDF00-\uDF35\uDF40-\uDF55\uDF60-\uDF72\uDF80-\uDF91]|\uD803[\uDC00-\uDC48\uDC80-\uDCB2\uDCC0-\uDCF2]|\uD804[\uDC03-\uDC37\uDC83-\uDCAF\uDCD0-\uDCE8\uDD03-\uDD26\uDD50-\uDD72\uDD76\uDD83-\uDDB2\uDDC1-\uDDC4\uDDDA\uDDDC\uDE00-\uDE11\uDE13-\uDE2B\uDE80-\uDE86\uDE88\uDE8A-\uDE8D\uDE8F-\uDE9D\uDE9F-\uDEA8\uDEB0-\uDEDE\uDF05-\uDF0C\uDF0F\uDF10\uDF13-\uDF28\uDF2A-\uDF30\uDF32\uDF33\uDF35-\uDF39\uDF3D\uDF50\uDF5D-\uDF61]|\uD805[\uDC00-\uDC34\uDC47-\uDC4A\uDC80-\uDCAF\uDCC4\uDCC5\uDCC7\uDD80-\uDDAE\uDDD8-\uDDDB\uDE00-\uDE2F\uDE44\uDE80-\uDEAA\uDF00-\uDF19]|\uD806[\uDCA0-\uDCDF\uDCFF\uDEC0-\uDEF8]|\uD807[\uDC00-\uDC08\uDC0A-\uDC2E\uDC40\uDC72-\uDC8F]|\uD808[\uDC00-\uDF99]|\uD809[\uDC80-\uDD43]|[\uD80C\uD81C-\uD820\uD840-\uD868\uD86A-\uD86C\uD86F-\uD872][\uDC00-\uDFFF]|\uD80D[\uDC00-\uDC2E]|\uD811[\uDC00-\uDE46]|\uD81A[\uDC00-\uDE38\uDE40-\uDE5E\uDED0-\uDEED\uDF00-\uDF2F\uDF40-\uDF43\uDF63-\uDF77\uDF7D-\uDF8F]|\uD81B[\uDF00-\uDF44\uDF50\uDF93-\uDF9F\uDFE0]|\uD821[\uDC00-\uDFEC]|\uD822[\uDC00-\uDEF2]|\uD82C[\uDC00\uDC01]|\uD82F[\uDC00-\uDC6A\uDC70-\uDC7C\uDC80-\uDC88\uDC90-\uDC99]|\uD835[\uDC00-\uDC54\uDC56-\uDC9C\uDC9E\uDC9F\uDCA2\uDCA5\uDCA6\uDCA9-\uDCAC\uDCAE-\uDCB9\uDCBB\uDCBD-\uDCC3\uDCC5-\uDD05\uDD07-\uDD0A\uDD0D-\uDD14\uDD16-\uDD1C\uDD1E-\uDD39\uDD3B-\uDD3E\uDD40-\uDD44\uDD46\uDD4A-\uDD50\uDD52-\uDEA5\uDEA8-\uDEC0\uDEC2-\uDEDA\uDEDC-\uDEFA\uDEFC-\uDF14\uDF16-\uDF34\uDF36-\uDF4E\uDF50-\uDF6E\uDF70-\uDF88\uDF8A-\uDFA8\uDFAA-\uDFC2\uDFC4-\uDFCB]|\uD83A[\uDC00-\uDCC4\uDD00-\uDD43]|\uD83B[\uDE00-\uDE03\uDE05-\uDE1F\uDE21\uDE22\uDE24\uDE27\uDE29-\uDE32\uDE34-\uDE37\uDE39\uDE3B\uDE42\uDE47\uDE49\uDE4B\uDE4D-\uDE4F\uDE51\uDE52\uDE54\uDE57\uDE59\uDE5B\uDE5D\uDE5F\uDE61\uDE62\uDE64\uDE67-\uDE6A\uDE6C-\uDE72\uDE74-\uDE77\uDE79-\uDE7C\uDE7E\uDE80-\uDE89\uDE8B-\uDE9B\uDEA1-\uDEA3\uDEA5-\uDEA9\uDEAB-\uDEBB]|\uD869[\uDC00-\uDED6\uDF00-\uDFFF]|\uD86D[\uDC00-\uDF34\uDF40-\uDFFF]|\uD86E[\uDC00-\uDC1D\uDC20-\uDFFF]|\uD873[\uDC00-\uDEA1]|\uD87E[\uDC00-\uDE1D])+/g
const DEBOUNCE_DELAY = 500

class SpellCheckManager {
  constructor($scope, $cacheFactory, $http, $q, adapter) {
    this.onChange = this.onChange.bind(this)
    this.onSessionChange = this.onSessionChange.bind(this)
    this.onContextMenu = this.onContextMenu.bind(this)
    this.onScroll = this.onScroll.bind(this)
    this.learnWord = this.learnWord.bind(this)
    this.$scope = $scope
    this.$http = $http
    this.$q = $q
    this.adapter = adapter
    this.$scope.spellMenu = {
      open: false,
      top: '0px',
      left: '0px',
      suggestions: []
    }
    this.inProgressRequest = null
    this.changedLines = []
    this.firstCheck = true

    this.$scope.$watch('spellCheckLanguage', (language, oldLanguage) => {
      if (language !== oldLanguage && oldLanguage != null) {
        return this.reInitForLangChange()
      }
    })
    this.$scope.replaceWord = this.adapter.replaceWord
    this.$scope.learnWord = this.learnWord

    this.cache =
      $cacheFactory.get(`spellCheck-cache`) ||
      $cacheFactory(`spellCheck-cache`, {
        capacity: 15000
      })

    this.selectedHighlightContents = null

    $(document).on('click', e => {
      // There is a bug (?) in Safari when ctrl-clicking an element, and the
      // the contextmenu event is preventDefault-ed. In this case, the
      // contextmenu event *and* a click event propagate from the element.
      // If the contextmenu is *not* preventDefault-ed, then only the
      // contextmenu event propagates. The latter behaviour is what other
      // browsers do no matter if the event is preventDefault-ed or not.
      // See: https://stackoverflow.com/questions/53660359/preventing-default-on-contextmenu-event-triggers-subsequent-click-event
      // This means that on Safari the spelling menu is opened in response to
      // the contextmenu event, but then quickly closed due to the
      // (propagated) click event.
      // We still need to handle the click event, to enable the "click-away"
      // behaviour. The workaround is to check if we're in Safari and the Ctrl
      // key is pressed in the click handler, and if so, then prevent the
      // spelling menu from closing.
      // That when clicking as normal, the "click-away" behaviour still works
      // as before.
      // When ctrl-clicking, the click event is not propagated, so the handler
      // is ignored. However this triggers another contextmenu event, which
      // closes the previous spelling menu.
      if (window._ide.browserIsSafari && e.ctrlKey) {
        return
      }

      // Ignore if right click
      if (e.which !== 3) {
        this.closeContextMenu()
      }
      return true
    })
  }

  init() {
    this.changedLines = Array(this.adapter.getLineCount()).fill(true)
    this.firstCheck = true
    if (this.isSpellCheckEnabled()) {
      this.runSpellCheckSoon(DEBOUNCE_DELAY)
    }
  }

  reInitForLangChange() {
    this.adapter.highlightedWordManager.reset()
    this.init()
  }

  isSpellCheckEnabled() {
    return !!(
      this.$scope.spellCheck &&
      this.$scope.spellCheckLanguage &&
      this.$scope.spellCheckLanguage !== ''
    )
  }

  onChange(e) {
    if (this.isSpellCheckEnabled()) {
      this.$scope.$applyAsync(() => {
        if (
          this.selectedHighlightContents &&
          this.selectedHighlightContents !== this.adapter.getSelectionContents()
        ) {
          this.closeContextMenu()
        }
      })
      this.markLinesAsUpdated(this.adapter.normalizeChangeEvent(e))
      this.adapter.highlightedWordManager.clearHighlightTouchingRange(e)
      this.runSpellCheckSoon(DEBOUNCE_DELAY)
    }
  }

  onSessionChange() {
    this.adapter.highlightedWordManager.reset()
    if (this.inProgressRequest != null) {
      this.inProgressRequest.abort()
    }

    if (this.isSpellCheckEnabled()) {
      this.runSpellCheckSoon(DEBOUNCE_DELAY)
    }
  }

  onContextMenu(e) {
    this.closeContextMenu()
    this.openContextMenu(e)
  }

  onScroll() {
    if (this.isSpellCheckEnabled()) {
      this.runSpellCheckSoon(DEBOUNCE_DELAY)
    }
    this.closeContextMenu()
  }

  openContextMenu(e) {
    const coords = this.adapter.getCoordsFromContextMenuEvent(e)
    const highlight = this.adapter.getHighlightFromCoords(coords)
    const shouldPositionFromBottom = this.adapter.isContextMenuEventOnBottomHalf(
      e
    )
    if (highlight) {
      this.adapter.preventContextMenuEventDefault(e)
      this.adapter.selectHighlightedWord(highlight)
      this.$scope.$applyAsync(() => {
        this.selectedHighlightContents = this.adapter.getSelectionContents()
        this.$scope.spellMenu = {
          open: true,
          top: coords.y + 'px',
          left: coords.x + 'px',
          layoutFromBottom: shouldPositionFromBottom,
          highlight
        }
      })
    }
  }

  closeContextMenu() {
    // This is triggered on scroll, so for performance only apply setting when
    // it changes
    if (
      (this.$scope != null ? this.$scope.spellMenu : undefined) &&
      this.$scope.spellMenu.open !== false
    ) {
      this.selectedHighlightContents = null
      this.$scope.$applyAsync(() => {
        this.$scope.spellMenu.open = false
      })
    }
  }

  learnWord(highlight) {
    this.apiRequest('/learn', { word: highlight.word })
    this.adapter.highlightedWordManager.removeWord(highlight.word)
    const language = this.$scope.spellCheckLanguage
    this.cache.put(`${language}:${highlight.word}`, true)
  }

  markLinesAsUpdated(change) {
    const { start } = change
    const { end } = change

    const insertLines = () => {
      let lines = end.row - start.row
      while (lines--) {
        this.changedLines.splice(start.row, 0, true)
      }
    }

    const removeLines = () => {
      let lines = end.row - start.row
      while (lines--) {
        this.changedLines.splice(start.row + 1, 1)
      }
    }

    if (change.action === 'insert') {
      this.changedLines[start.row] = true
      insertLines()
    } else if (change.action === 'remove') {
      this.changedLines[start.row] = true
      removeLines()
    }
  }

  runSpellCheckSoon(delay) {
    if (delay == null) {
      delay = 1000
    }
    const run = () => {
      delete this.timeoutId
      this.runSpellCheck()
    }
    if (this.timeoutId != null) {
      clearTimeout(this.timeoutId)
    }
    this.timeoutId = setTimeout(run, delay)
  }

  runSpellCheck() {
    let j
    let i, key, word
    const rowNumsToCheck = this.getRowNumsToCheck()
    const language = this.$scope.spellCheckLanguage
    let { words, positions } = this.getWords(rowNumsToCheck)

    const highlights = []
    const seen = {}
    const newWords = []
    const newPositions = []

    // iterate through all words, building up a list of
    // newWords/newPositions not in the cache
    for (j = 0, i = j; j < words.length; j++, i = j) {
      word = words[i]
      key = `${language}:${word}`
      if (seen[key] == null) {
        seen[key] = this.cache.get(key)
      } // avoid hitting the cache unnecessarily
      const cached = seen[key]
      if (cached == null) {
        newWords.push(words[i])
        newPositions.push(positions[i])
      } else if (cached === true) {
        // word is correct
      } else {
        highlights.push({
          column: positions[i].column,
          row: positions[i].row,
          word,
          suggestions: cached
        })
      }
    }
    words = newWords
    positions = newPositions

    const displayResult = highlights => {
      if (this.timeoutId != null) {
        return
      }
      this.firstCheck = false
      rowNumsToCheck.forEach(row => {
        this.changedLines[row] = false
        this.adapter.highlightedWordManager.clearRow(row)
      })
      highlights.map(highlight =>
        this.adapter.highlightedWordManager.addHighlight(highlight)
      )
    }

    if (!words.length) {
      displayResult(highlights)
    } else {
      this.inProgressRequest = this.apiRequest(
        '/check',
        { language, words },
        (error, result) => {
          delete this.inProgressRequest
          if (error != null || result == null || result.misspellings == null) {
            return null
          }
          const misspelled = []
          for (let misspelling of result.misspellings) {
            word = words[misspelling.index]
            const position = positions[misspelling.index]
            misspelled[misspelling.index] = true
            highlights.push({
              column: position.column,
              row: position.row,
              word,
              suggestions: misspelling.suggestions
            })
            key = `${language}:${word}`
            if (!seen[key]) {
              this.cache.put(key, misspelling.suggestions)
              seen[key] = true
            }
          }
          for (i = 0; i < words.length; i++) {
            word = words[i]
            if (!misspelled[i]) {
              key = `${language}:${word}`
              if (!seen[key]) {
                this.cache.put(key, true)
                seen[key] = true
              }
            }
          }
          displayResult(highlights)
        }
      )
    }
  }

  apiRequest(endpoint, data, callback) {
    if (callback == null) {
      callback = function(error, result) {
        console.error(error)
      }
    }
    data.token = window.user.id
    data._csrf = window.csrfToken
    // use angular timeout option to cancel request if doc is changed
    const requestHandler = this.$q.defer()
    const options = { timeout: requestHandler.promise }
    this.$http
      .post(`/spelling${endpoint}`, data, options)
      .then(response => {
        return callback(null, response.data)
      })
      .catch(response => {
        return callback(new Error('api failure'))
      })
    // provide a method to cancel the request
    const abortRequest = () => requestHandler.resolve()
    return { abort: abortRequest }
  }

  getWords(rowNumsToCheck) {
    const lines = this.adapter.getLinesByRows(rowNumsToCheck)
    const words = []
    const positions = []
    for (let row = 0; row < lines.length; row++) {
      let line = lines[row]
      let rowIdx = rowNumsToCheck[row]
      line = this.blankOutBlacklistedCommands(line)
      var result
      WORD_REGEX.lastIndex = 0 // reset global stateful regexp for this usage
      while ((result = WORD_REGEX.exec(line))) {
        let word = result[0]
        if (word[0] === "'") {
          word = word.slice(1)
        }
        if (word[word.length - 1] === "'") {
          word = word.slice(0, -1)
        }
        positions.push({ row: rowIdx, column: result.index })
        words.push(word)
      }
    }
    return { words, positions }
  }

  // Returns row numbers for dirty lines (i.e. with changes, need to be checked).
  // Initially, all lines are considered to be dirty/have changes (i.e. weren't checked before).
  // Generally, only the visible viewport is considered. Upon initialization, a larger area is
  // considered (visible viewport ± 2x the size of the visible viewport).
  //
  // Examples:
  // 1. Document with 10 lines; initial check
  //    Viewport show lines 3 to 7
  //    Initial check means that we are going to also check the area above and below the visible viewport
  //    Extra area to be checked is 2x the size of visible viewport (5 visible lines; 2 * 5 = 10), i.e.
  //      3 - 10 = -7 (clamped to 0, the lower boundary of document lines)
  //      7 + 10 = 17 (clamped to 9, the upper boundary of document lines)
  //    Expected result: [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
  // 2. Document with 10 lines; document has already been initially checked; user changes lines 5 and 6
  //    Viewport show lines 3 to 7
  //    Expected result: [ 5, 6 ] (i.e. unchanged lines are ignored; intersection of viewport and changed lines)
  // 3. Document with 10 lines, document has already been initially checked, remote user changes lines 1 and 2
  //    Viewport show lines 3 to 7
  //    Expected result: [ ] (i.e. changes were outside viewport, so there are no visible changed lines)
  getRowNumsToCheck() {
    const firstVisibleRowNum = this.adapter.getFirstVisibleRowNum()
    const lastVisibleRowNum = this.adapter.getLastVisibleRowNum()
    let firstRowNumtoCheck = firstVisibleRowNum
    let lastRowNumtoCheck = lastVisibleRowNum

    if (this.firstCheck) {
      const lastRowNum = this.adapter.getLineCount() - 1
      const nVisibleLines = lastVisibleRowNum - firstVisibleRowNum + 1
      firstRowNumtoCheck = Math.max(0, firstVisibleRowNum - 2 * nVisibleLines)
      lastRowNumtoCheck = Math.min(
        lastVisibleRowNum + 2 * nVisibleLines,
        lastRowNum
      )
    }

    return this.changedLines.reduce((rowNumsToCheck, curVal, curRow) => {
      if (
        curVal &&
        curRow >= firstRowNumtoCheck &&
        curRow <= lastRowNumtoCheck
      ) {
        rowNumsToCheck.push(curRow)
      }
      return rowNumsToCheck
    }, [])
  }

  blankOutBlacklistedCommands(line) {
    return line.replace(BLACKLISTED_COMMAND_REGEX, command =>
      Array(command.length + 1).join('.')
    )
  }
}

export default SpellCheckManager
